#include<stdio.h>
#include<windows.h>
#define maxn 100

int main()
{
	int i,count;
	i=0;
	count=0;
	char s[maxn];
	gets(s);
	while (s[i++]!='\0')
	{
		switch(s[i-1])
		{
			case '0':count++; break;
			case '1':count++; break;
			case '2':count++; break;
			case '3':count++; break;
			case '4':count++; break;
			case '5':count++; break;
			case '6':count++; break;
			case '7':count++; break;
			case '8':count++; break;
			case '9':count++; break;
		}
	}
	printf("%d\n",count);
	system("pause");
	return 0;
}
